Method and apparatus for improved depth matching of borehole images or core images

a technology of depth matching and boreholes, applied in seismology for waterlogging, instruments, reradiation, etc., can solve the problems of uniform motion, inconvenient use, and inability to accurately match the depth of the borehole,
US7346454B2Inactive Publication Date: 2008-03-18SCHLUMBERGER TECH CORP
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Patents(United States)
Current Assignee / Owner
SCHLUMBERGER TECH CORP
Publication Date
2008-03-18
Estimated Expiration
Not applicable · inactive patent

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Abstract

A method for depth matching borehole images and / or core section images is disclosed wherein signals from sensors at different levels on a logging tool are converted into an averaged signal representing the average bed signal at the center of the borehole at each of the different levels. A depth matching technique is applied to the averaged signals from the sensors at different levels on the logging tool to determine the optimum depth offset necessary for matching two sets of signals from sensors at the different levels of the logging tool. In an alternative embodiment of the invention a Hough transform is utilized to process the well log images and generate three-dimensional images in Hough space. The three dimensional images are converted into two-dimensional extremum curves. Depth matching is performed on the two dimensional extremum curves to calculate an offset to match the two dimensional extremum curves. The calculated offset is then applied to the well log images to depth match them.
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Description

FIELD OF THE INVENTION

[0001] This invention relates to logging of boreholes. More specifically, the invention relates to a method for improving correlation of core images, borehole images and well logging data derived from sensors located on a well logging tool as it passes through a borehole.BACKGROUND OF THE INVENTION

[0002] In a typical prior art oil well logging scenario, a string of well logging tools having multiple sensors for measuring characteristics of the earth formation along the wall of a borehole is lowered via a cable to the bottom of the borehole. Geophysical data is recorded by way of the sensors as the cable is wound in using a precision winch. The depth in the earth at which the sensors on the logging tools are positioned as data is logged is determined by measuring the logging speed and cable depth. Devices such as a depth wheel measurement instrument and an axial accelerometer may be utilized.

[0003] Typically, measurements taken along the length of a borehole by log...

Claims

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